Missouri executed early on Wednesday a Kansas City man convicted of killing a gas station attendant in front of the attendant’s stepdaughter during a robbery 20 years ago.

Leon Taylor, 56, was pronounced dead at 12:22 a.m. local time on Wednesday at a Missouri state prison following a lethal injection, Missouri Department of Corrections spokesman Mike O’Connell said in a statement.

Taylor shot Newton in the head as Newton’s 8-year-old stepdaughter watched. She testified that Taylor had tried to shoot her as well but the gun jammed.

Taylor’s lawyers had sought to have the U.S. Supreme Court stay the execution but the court denied the request without comment, according to court documents.

“Robert Newton was murdered in cold blood, even after he handed over money during a robbery of the gas station he managed,” Nixon said in a statement.

“There is no question of guilt in this murder,” he said.

Taylor was the ninth inmate executed in Missouri in 2014 and the 33rd person executed in the United States this year, according to the Death Penalty Information Center.

Part of Taylor’s appeal was tied to a 2002 ruling by the Supreme Court that found only a jury, and not a judge, could impose a death sentence. Racial discrimination also played a role, according to Taylor’s attorneys.

The mixed-race jury in Taylor’s first trial deadlocked on a sentence and a judge sentenced him to death. Taylor appealed and in a second punishment trial an all-white jury ordered the death sentence. Taylor was black and Newton was white.

Taylor’s attorneys also contended that the execution should have been postponed until there was a ruling in a lawsuit brought by several Missouri inmates, including Taylor, against the state over its lethal injection protocols.

(Reporting by Carey Gillam in Kansas City, Ian Simpson in Washington, and Curtis Skinner in San Francisco; Editing by Bill Trott, Mohammad Zargham and Paul Tait)